A user access device communicates with a convergence router by using a pseudo wire (Pseudo Wire, PW), the convergence router terminates the PW, and then forwards data to a target network device by using a routing protocol or relying on a Layer 3 virtual private network of the routing protocol (hereinafter abbreviated as L3VPN, Layer 3 Virtual Private network). Specifically, the convergence router communicates with the user access device by using a PW through a Layer 2 virtual Ethernet (L2VE) interface, and communicates with the target network device by using the routing protocol and relying on the L3VPN of the routing protocol through the Layer 3 virtual Ethernet (L3VE) interface, and the virtual Ethernet interface group (VE Group) is configured on the convergence router to bind the L2VE interface to the L3VE interface, so as to achieve the function of terminating traffic on Layer 2 and forwarding on Layer 3.
In order to protect users' services, the user access device connects to their respective L2VE interfaces of the primary and secondary convergence routers by using the primary and secondary PW, and the primary and secondary convergence routers then connect to the target network device through their respective L3VE interfaces. The traffic may be quickly switched to the secondary PW after the primary PW fails; and after failure recovery of the primary PW, the traffic may be switched back to the primary PW after a period of preset time.
To facilitate understanding, referring to FIG. 1, networking under the scenario of the Internet protocol backhaul network (Internet Protocol Backhaul Network, IP Backhaul) is illustrated. Abase transceiver station (Base Transceiver Station, BTS) (101) is equivalent to a user-side network device; a cell side gateway (Cell Site Gateway, CSG) (102) is equivalent to a user access device, which may be an access router supporting PW function, and be configured to access to the user-side network device; a radio service gateway (Radio Service Gateway, RSG) 1 (103) and an RSG2 (104) are equivalent to a convergence router; and a radio network controller (Radio Network Controller, RNC) (105) is equivalent to a target network device.
The RSG1 (103) communicates with the CSG (102) by using a PW (106), where the PW (106) is the primary PW under normal circumstances; the RSG1 (103) communicates with the RNC (105) through an L3VPN (112). The RSG1 (103) is configured with an L2VE interface (108) and an L3VE interface (109), and a VE Group is established on the RSG1 to bind the L2VE interface (108) to the L3VE interface (109). The L2VE interface (108) is connected to the primary PW (106), and the L3VE interface (109) is connected to the L3VPN (112).
The RSG2 (104) communicates with the CSG (102) by using a PW (107), where the PW (107) is a secondary PW under normal circumstances; the RSG2 (104) is configured with an L2VE interface (110) and an L3VE interface (111), and a VE Group is established on the RSG2 to bind the L2VE interface (110) to the L3VE interface (111). The L2VE interface (110) is connected to a secondary PW (107), and the L3VE interface (111) is connected to an L3VPN (113).
The uplink traffic refers to the traffic from the BTS (101) to the RNC (105), and the downlink traffic refers to the traffic from the RNC (105) to the BTS (101).
In prior art, in the uplink traffic direction, the CSG (102) regularly sends an address resolution protocol (Address Resolution Protocol, ARP) of the user-side network device BTS (101) to the RSG1 (103) and the RSG2 (104) simultaneously; the L3VE interface (109) and the L3VE interface (111) are simultaneously set at the up state, the RSG1 (103) and the RSG2 (104) respectively release routes to the RNC (105), so that the RNC (105) has two routes to choose from in the downlink direction, and the RNC (105) may select one according to the route selection rules, such as BGP attribute.
Under normal circumstances, the uplink traffic is forwarded by using the primary PW, and the uplink traffic passes through the following nodes: the BTS (101)->the CSG (102)->the RSG1 (103)->the RNC (105). If it is assumed that the RNC (105) selects the route to the RSG1 in the downlink traffic direction, that is, the downlink traffic passes through the following nodes: the RNC (105)->the RSG1 (103)->the CSG (102)->the BTS (101).
If the PW (106) fails and changes to be in the down state, the PW (106) changes to be in the secondary state, and therefore the L3VE (109) is triggered to be in the down state and the route to the RSG1 (103) on the RNC (105) is deleted, and simultaneously ARP of the BTS (101) on the RSG1 (109) is triggered to be deleted. The RNC (105) immediately switches the traffic in the downlink direction to the RSG2 (104), so that nodes through which the downlink traffic passes are the RNC (105)->the RSG2 (104)->the CSG (102)->the BTS (101). In this case, the primary and secondary PWs are switched, the PW (107) changes to be the primary PW, and the path through which the uplink traffic that selects the PW (107) passes is the same as the path through which the downlink traffic passes, that is, nodes through which the uplink traffic passes are the BTS (101)->the CSG (102)->the RSG2 (104)->the RNC (105).
The PW (106) changes to be in the up state due to failure recovery of the PW (106) after a period of time. In this case, the PW (106) is still in the secondary state and, after a period of preset time, changes to be in the primary state after a second primary and secondary switch, then the PW (107) changes to be in the secondary state and the L3VE (109) is triggered to be in the up state, and the RNC (105) switches the downlink traffic path to the RSG1 (103). However, after the PW (106) re-changing to be in the up state, the RNC (105) may only re-learn ARP of the user-side network device after a period of time, and the downlink traffic encounters packet loss in this period of time.